Vehicular air-pollution preventive system

ABSTRACT

A VEHICULAR AIR-POLLUTION PREVENTIVE SYSTEM FOR USE WITH AN INTERNAL COMBUSTION ENGINE, WHICH SYSTEM IS ADAPTED TO REDUCE THE QUANTITY OF NITROGEN OXIDES PRODUCED DURING ACCELERATION OR HILL-CLIMBING IN SUCH QUANTITIES AS TO CAUSE A SERIOUS AIR-POLLUTION PROBLEM ESPECIALLY WHEN THE VEHICLE IS DRIVE IN URBAN AREAS, HAVING TWO SWITCHES CLOSING WHEN THE VEHICLE IS DRIVEN AT A SPEED   FALLING WITHIN A PREDETERMINED RANGE ANS WITH THE INTAKE MANIFOLD VACUUM LOWR THAN A PREDETERMINED LEVEL PROVIDING ACCELERATION OR HILL-CLIMBING AND AN EXHAUST RECICULATION CONTROL VALVE ASSEMBLY WHICH IS ADAPTED TO PASS THE EXHAUST GASES TO THE INTAKE MANIFOLD WHEN BOTH OF THE TWO SWITCHES ARE CLOSED CONCURRENTLY.

Sept. 20, 1971 suo NAKAJIMA EI'AL 3,605,709

VEHICULAR AIR-POLLUTION PREVENTIVE SYSTEM Filed March 11, 1970 4Sheets-Sheet l C I 5- I i j TIME- I I I VEHICLE SPEED I I I 2000- 1 IOOOQUANTITY OF NOX TIME THROTTLE FULLY -\OPEN INTAKE MAN I FOLD VACUUM,

20 60 DO I40 VEHICLE SPEED, km/hr Sept. 20, 1971 YASUO NAKAJIMA ETAL31605109 VEHICULAR AIR-POLLUTION PREVENTIVE SYSTEM Filed March 11, 19704 Sheets-Sheet 2 'Se tJ 2117971 YASUO NAKAJIMA ETAL 3,605,709

VEHICULAR AIR-POLLUTION PREVENTIVE SYSTEM Filed March 11, 1970 4Sheets-Sheet Sept. 20, 1971 YASUQ NAKAJIMA EI'AL 3,605,709

VEHICULAR AIR-POLLUTION PREVENTIVE SYSTEM Filed March 11, 1970 4Sheets-Sheet 4 United States Patent Olfice U.S. Cl. 123119A ClaimsABSTRACT OF THE DISCLOSURE A vehicular air-pollution preventive systemfor use with an internal combustion engine, which system is adapted toreduce the quantity of nitrogen oxides produced during acceleration orhill-climbing in such quantities as to cause a serious air-pollutionproblem especially when the vehicle is driven in urban areas, having twoswitches closing when the vehicle is driven at a speed falling within apredetermined range and with the intake manifold vacuum lower than apredetermined level providing acceleration or hill-climbing and anexhaust recirculation control valve assembly which is adapted to passthe exhaust gases to the intake manifold when both of the two switchesare closed concurrently.

This invention relates to a vehicular air-pollution preventive systemand, more particularly, to a system adapted to reduce the quantity oftoxic nitrogen oxides contained in engine exhaust gases.

Air pollution resulting from the emission of nitrogen oxides is one ofthe serious public nuisances particularly in urban areas of today and itis during acceleration and hill-climbing of a motor vehicle thatnitrogen oxides are discharged to the open air in such quantities as tocause a serious air-pollution problem in the urban areas. This will meanthat the air-pollution problem could be alleviated significantly if thequantity of nitrogen oxides is reduced during acceleration andhill-climbing that occur frequently when the motor vehicle is driven inurban areas.

In order to reduce the quantity of nitrogen oxides in the engine exhaustgases, various attempts have been made including a scheme ofcontinuously recirculating the engine exhaust gases to the intakemanifold of the engine. In this known practice, the engine exhaust gasesare partially recirculated in a continuous fashion to the intakemanifold where a regulated amount of inert gases are added to therecirculated exhaust gases to lower the temperature at which the exhaustgases are burned for a second time. This reduction in the flametemperature prevents reaction that would otherwise take place betweennitrogen and oxygen in the exhaust gases. Thus, the quantity of nitrogenoxides contained in the finally discharged exhaust gases can be reducedsignificantly without detriment to the performance quality of theengine.

In spite of the prominent reduction in the quantity of nitrogen oxidesin the exhaust gases, continuous recirculation of the exhaust gaseswithout respect of the operating conditions of the engine, as has thusfar been the practice, results in unstable engine operation, decreasedengine output and contamination within the engine and, as such, isconsidered unsuitable for practical purposes.

The invention was thus completed under the recognition that thedrawbacks which result from the continuous recirculation of the exhaustgases can be effectively eliminated by selectively recirculating theexhaust gases only 3,605,709 Patented Sept. 20, 1971 when the engine isdriven under predetermined conditions in which the motor vehicleaccelerates or climbs up a hill as frequently experienced in the drivingin urban areas.

Such conditions of the engine providing the acceleration orhill-climbing of the motor vehicle are represented, as preferableaccording to the invention, by the combination of the vacuum in theintake manifold of the engine and the vehicle speed.

A primary object of the invention is therefore to provide a system forreducing the quantity of nitrogen oxides emitted from the engine whenthe motor vehicle is driven in urban areas.

Another primary object of the invention is to provide a system which isadapted to reduce the quantity of nitrogen oxides in the engine exhaustgases without detriment to the operation stability and power output ofthe engine and without contamination of the engine components.

Still another primary object of the invention is to provide a systemwhich is constructed and arranged to have the exhaust gases recirculatedinto the intake manifold only when the motor vehicle is accelerated orclimbs up a hill at a speed within a predetermined range and with theintake manifold vacuum lower than a predetermined level.

In the drawings:

FIG. 1 is a graphical representation of a typical example of therelationships between the vehicle speed of a motor vehicle running oncity-roads and the quantity of nitrogen oxides in the then emittedexhaust gases;

FIG. 2 is a schematical view showing a preferred embodiment of theair-pollution preventive system according to the invention as combinedwith a usual automotive internal combustion engine which is shown in aschematical end view;

FIG. 3 is a section on line II of FIG. 2;

FIG. 4 is a graphical representation exemplifying a region in which thesystem shown in FIGS. 2 and 3 is operable;

FIG. 5 is similar to FIG. 2 but shows a modification of the system showntherein; and

FIG. 6 is also similar to FIG. 2 but shows another modification.

The quantity of nitrogen oxides contained in the engine exhaust gases isintimately related to the vehicle speed. The investigations conducted bythe inventors have revealed that it is during acceleration andhill-climbing that the quantity of nitrogen oxides increases to such anextent as to cause a serious air-pollution problem in urban areas. Thiswill be ascertained by reference to FIG. 1, which shows that as thevehicle speed is increased from a to b for acceleration or c to d forhill-climbing, the quantity of nitrogen oxides increases abruptly asindicated by the broken curve a'b' or c'd', respectively. Thus, theemission of nitrogen oxides could be reduced effectively throughout thevarying modes of vehicular operations if the emission is minimizedduring acceleration and hill-climbing.

In order to realize such scheme, the invention proposes, as preferable,to have the ranges a-b and cd of the driving conditions of the vehiclerepresented by the combination of intake manifold vacuum and vehiclespeed.

A preferred embodiment to accomplish such an end is shown in FIGS. 2 and3.

As best seen in FIG. 2, the system according to the invention is used incombination with a usual automotive internal combustion engine which isgenerally designated by reference numeral 1. The engine 1 has, ascustomary, an intake manifold 2 and exhaust manifold 3 and is combinedwith a carburettor 4 which is removed from FIG.

4 for simplicity of illustration. The carburettor 4 is anyway mounted onthe intake manifold 2 by a mounting flange 5 and, as illustrated in FIG.3, has a throttle valve 6 which is mounted on and rotatable with arotary shaft 6a, as customary.

The air-pollution preventive system of the invention essentialiycomprises an exhaust recirculation control valve assembly 10, which isactually a solenoid valve device. The valve assembly 10 has a casing 11having formed therein a chamber 12 which communicates on one side Withthe exhaust manifold 3 through an exhaust recirculation conduit 13 andon the other with the carburettor 4 downstream of the throttle valve 6through an exhaust recirculation nozzle 14. If preferred, the nozzle 14may be opened into the intake manifold 2, though not so illustrated. Anorifice 14:: may be provided in the passage 14 thereby to control theflow of air flowing therethrough.

A valve element 15 is operatively mounted in the chamber 12 and ispositioned relative to a valve seat 16 forming part of the inner wall ofthe chamber 12. The valve element 15 is integrally combined with ahollow cylinder 17 which is axially movably mounted in the chamber 12.The hollow cylinder 17 has accommodated therein a compression spring 18so that the hollow cylinder 17 is forced in a direction in which thevalve element 15 is seated on the valve seat 16 to block thecommunication between the conduit 13 and nozzle 14. The hollow cylinder17 also serves as a moving core which is actuated into motion by asolenoid coil 19 and is powered by a suitable source 20 of electricenergy through a line 21.

The exhaust recirculation control valve assembly 10 thus constructed isoperated by control means which is responsive to the driving conditionsof the motor vehicle so that the valve element 15 is moved to and seatedon the valve seat 16 when predetermined driving conditions are respondedto by the control means.

The control means is arrange-d according to the invention to beresponsive to the vacuum in the intake manifold 2 of the engine and thevehicle speed selected by a transmission system which is generallydesignated by numeral 7.

The control means may be, as illustrated in FIG. 4, comprisedessentially of a vacuum switch 22 and vehicle speed switch 23, which areconnected in series with the solenoid coil 19 of the control valveassembly 10 through a line 21.

The vacuum switch 22 is connected with and controlled by a diaphragmdevice 24, which is intended to detect the vacuum in the intake manifold2. The diaphragm device 24 has a vacuum chamber 25 and atmosphericchamber 26 which is separated from the former by a diaphragm member 27.The vacuum chamber 25 communicates with the intake manifold 2 of theengine 1 through a vacuum conduit 28, while the atmospheric chamber 26is vented from the atmosphere. The diaphragm member 27 is connected withthe vacuum switch 22 through a connecting rod 29 extending through theatmospheric chamber 26. In the vacuum chamber 27 is mounted acompression spring 30 whereby the diaphragm member 27 is forced towardthe atmospheric chamber 25. Thus, when the intake manifold vacuum is atan elevated level, the diaphragm member 27 is forced toward the vacuumchamber 25 against the action of the spring 30 thereby to keep theswitch 22 open. When, in contrast, the intake manifold vacuum dropsunder a predetermined level of, for instance, 350 mm. of Hg, then thespring 30 overpowers the vacuum and the diaphragm member 27 is movedtoward the atmospheric chamber 26 to permit the switch 22 to close. Thecompression of the spring 30 may be determined in a manner to yield tothe vacuum at such predetermined level.

The vehicle speed switch 23, on the other hand, is operated by a vehiclespeed detector 31 which is driven by the output shaft (not identified)of the transmission system 7 through a driving shaft 32 so as to detectthe revolution speed of the output shaft of the transmission system. Thevehicle speed detector 31 delivers voltages proportional to the whichspeeds detected thereby and energizes the switch 23. The switch 23 maybe constructed as a normallyopen relay switch which is arranged to closewhen it is energized with a voltage corresponding to a vehicle speedranging from 20 to km./hr., by way of example.

The vehicle speed detector 31 is herein shown as connected with a speedmeter 33 which visibly indicates the vehicle speed selected in thetransmission system from time to time. Denoted by 34 is an ignitionswitch which may be interposed, if desired, between the vehicle speedswitch 23 and power source 20.

When, in operation, the engine is driven under conditions in which thequantity of nitrogen oxides contained in the engine exhaust gases is notsuch that will cause a serious air-pollution problem as duringdeceleration or normal cruising, then the intake manifold vacuum and/ orthe vehicle speed will be outside the range within which the vacuumswitch 22 and/or vehicle speed switch 23 are to be closed. In thisparticular condition, the solenoid coil 19 of the control valve assembly10 is kept disconnected from the source 20 of power and thus remainsunexcited. As the consequence, the valve element 15 remains seated onthe valve seat 16 by the action of the compression spring 18, isolatingthe intake manifold 2 from the exhaust manifold 3. The exhaust gases arein this manner prohibited from entering the nozzle 14 through thechamber 12.

When, on the other hand, the engine output increases to such an extentas to produce nitrogen oxides in quantities to cause a serious pollutionproblem as represented by the dotted curves ab or c'd in FIG. 1, thenthe intake manifold vacuum drops under the aforesaid predeterminedlevel, for example, 350 mm. of Hg and the vehicle speed falls within thepredetermined range of, for instance, 20 to 80 km./ hr. In thiscondition, the spring 30 overpowers the vacuum in the vacuum chamber 25to cause the diaphragm member 27 to move into a position in which theswitch 22 is closed. At the same time, the relay switch 23 is energizedwith a voltage supplied from the detector 31 and closed consequently.The two switches 22 and 23 thus closed concurrently, the solenoid coil19 of the control valve assembly 10 is now energized to cause the valveelement 15 to be unseated from the valve seat 16 against the action ofthe spring 18, thereb passing the exhaust gases from the conduit 13 tonozzle 14. The exhaust gases are thus recirculated into the intakemanifold so that the nitrogen oxides contained in the finally dischargedexhaust gases are reduced from the level indicated by the broken curvea'b' or c-d' down to the level indicated by the solid curve a'-b' orc'a", respectively, as shown in FIG. 1.

In order to prevent the intake manifold and engine from beingcontaminated with the exhaust gases recirculated, a filter 13a may beprovided in the recirculation conduit so as to remove carbons from theexhaust gases.

The exhaust recirculation control valve assembly which has been shown asa solenoid valve device 10 may be constructed otherwise inasmuch as theintent of recirculating the exhaust gases only when the engine is drivenat predetermined speeds and the intake manifold vacuum lowered under apredetermined level, one of such modifications being illustrated in FIG.4.

The embodiment shown in FIG. 5 is adapted to protect the solenoid devicefrom contamination with exhaust gases.

As shown, the exhaust recirculation control valve is now constructed asa combination of a spool valve device 35 and a solenoid valve device 36to control the former.

The spool valve device 36 has a casing 37 communicating on one side withthe exhaust manifold 3 through a conduit 38 and on the other with theintake manifold 2 through a nozzle 39. The conduit 38 is shown todebouch into the casing 37 at an inlet port 38a and the nozzle 39 tolead from the casing at an outlet port 39a. An orifice 45 may beprovided in the nozzle 39 to control the flow through the nozzle.

The casing 37 has accommodated therein a spool valve 41 having a land42. A compression spring 43 is mounted in a chamber 44 formed betweenthe end walls of the casing 37 and land 42 in such a manner that thespool 41 is forced toward a position in which the inlet port 38a isclosed by the land 42, as shown.

The casing 37 further communicates with a casing 45 of the solenoiddevice 36 through a conduit 46. This casing 45 in the solenoid valvedevice 37 communicates on one side with the intake manifold 2 through aconduit 47 and on the other with the atmosphere, or with an cleaner ifpreferred, through a conduit 48. A moving core 49 is axially movablymounted in the casing 45 to act as a valve member and a compressionspring 50 is mounted around this moving core or valve member 49 in amanner to force the valve member toward a position in which the conduit47 is closed and the conduit 48 opened. In this condition, the casing 45is prevented for communicating with the intake manifold 2 and ismaintained at an atmospheric pressure.

The valve member 49 is operated by a solenoid coil 51 which is connectedat one end with a power source 20 through a line 21a and at the otherwith a vacuum switch 20 and vehicle speed switch 24 through a line 21bsimilarly to the system illustrated in FIG. 2.

The switches 22 and 23 are controlled by a diaphragm device 24 andvehicle speed detector 31, respectively, which are entirely similar inconstruction and function to those shown in FIG. 2 so that thediscussion previously given applies thereto.

During deceleration or normal cruising of the motor vehicle when theemission of nitrogen oxides from the engine is too low in concentrationto cause a serious airpollution problem, the solenoid valve device 36remains inoperative because the solenoid coil 51 thereof is keptde-energized with the switches 22 and/or 23 open.

When, on the other hand, the engine output increases and nitrogen oxidesare produced from the engine in quantities that can not be neglectedfrom the practical standpoint as indicated by the dotted curves a'-b'and c'd' in FIG. 1, then the intake manifold vacuum decreases under apredetermined level to yield to the compression of the spring 28 of thediaphragm device 24 and concurrently the vehicle is driven at a speedwithin a predetermined range to cause the vehicle speed switch 23 to beactuated. The switches 22 and 23 are now closed and the solenoid coil 51of the solenoid valve device 36 energized. The valve member 49 is movedagainst the action of the spring 50 to a position to open the conduit 47and close the conduit 48. The intake manifold vacuum that is now at alower level is permitted to flow into the chamber 44 formed by the endwalls of the casing 37 and land 42 of the spool valve 41.

The spring 43 being selected to yield to the thus lowered vacuum, thespool valve 41 is pulled by the vacuum over to a position in which theland 42 leaves and opens the inlet port 38a. The conduit 38 is permittedto com municate with the nozzle 39 to enable the exhaust gases torecirculate from the exhaust manifold 3 into the intake manifold 2.

As an alternative to the spool valve device 35 used in theabove-described embodiment, a diaphragm valve device may be combinedwith the solenoid valve device to constitute an exhaust recirculationcontrol assembly in the system according to the invention, example beingshown in FIG. 5.

In FIG. 6, only the diaphragm valve device which is generally denoted by52 and the solenoid valve device which is similar to the counterpart inFIG. and is numbered accordingly are illustrated, because the remaining6 essential elements are the same as used in the system in FIG. 5.

Referring to FIG. 6, the diaphragm valve device 52 is constructedsimilarly to the diaphragm device 24 in FIG. 2, and has a vacuum chamber53 defined by a diaphragm member 54 and the structural wall of thedevice 52, as shown. The vacuum chamber 53 communicates with the casing45 of the solenoid valve device 36 through a conduit 46a. A valveelement 55 is connected with the diaphragm member 54 on its sideopposite to the vacuum chamber 53. A compression spring 56 is mounted inthe vacuum chamber 53 in a manner to force the diaphragm member 54 andaccordingly the valve element 55 away from the vacuum chamber 53. Thevalve element 55 in this protruded position projects into a port 57betweeen an exhaust recirculation conduit 38 and nozzle 39 thereby toisolate the conduit and nozzle from each other.

Now, as the engine output increases and the switches 22 and 23 areclosed, then the solenoid valve device 36 becomes actuated to permit thevacuum to flow into the vacuum chamber 53. The compression spring 56 isselected so as to yield to the vacuum so that the diaphragm member 54and accordingly the valve element 55 are moved toward the vacuum chamber53 and away from the port 57. With valve element 55 thus retracted, theconduit 38 communicates with the nozzle 39 thereby to pass the exhaustgases from the exhaust manifold to the intake manifold, similarly to thepreviously described embodiments.

What is claimed is:

1. An air-pollution preventive system for a motor vehicle having aninternal combustion engine with a carburetor, comprising control meansresponsive to the intake manifold vacuums and vehicle speeds at whichthe motor vehicle is driven for acceleration or hill-climbing and anexhaust recirculation control assembly having a chamber to providecommunication between the intake manifold and the exhaust manifold ofthe engine and a valve element operatively mounted in said chamber andnormally held by a spring action in a position to block saidcommunication, said valve element being moved by said control meansagainst said spring action to a position in which said chambercommunicates with the intake manifold when said control means detectssaid intake manifold vacuums and vehicle speeds whereby the exhaustgases are recirculated from the exhaust manifold to the intake manifoldof the engine.

2. A system according to claim 1, wherein said exhaust recirculationcontrol valve assembly comprises a solenoid coil, a hollow moving coreintegral with said valve element and movably mounted in said chamber, acompression spring mounted within said hollow moving core and forcingthe moving core to a position in which said valve element blocks saidcommunication, an exhaust recirculation conduit communicating with theexhaust manifold and leading into said chamber, and an exhaustrecirculation nozzle leading from said chamber downstream of said valveelement to the intake manifold, said valve element being unseated whensaid solenoid coil is energized to cause said moving core to move to itsretracted position whereby said conduit communicates with said nozzle.

3. A system according to claim 1, wherein said control valve assemblyincludes a spool valve device and a solenoid valve device, said spoolvalve device including a casing communicating on one side with theexhaust manifold through an exhaust recirculation conduit and on theother with the intake manifold through an exhaust recirculation nozzle,a spool valve axially movably mounted in said casing and having a landat one end, and a compression to a position in which said land is movedto a position in which said conduit communicates with said nozzle whensaid solenoid coil of said solenoid valve device is excited by means ofsaid control means.

4. A system according to claim 1, wherein said control valve assemblyincludes a diaphragm valve device and a solenoid valve device, saiddiaphragm valve device including a vacuum chamber, a diaphragm memberseparating said vacuum chamber from the atmosphere, a port communicatingon one side with the exhaust manifold through an exhaust recirculationconduit and on the other with the intake manifold through an exhaustrecirculation nozzle, a valve element connected with said diaphragmmember and directed toward said port, and a compression spring mountedin said vacuum chamber to force said diaphragm member toward a positionin which said valve element closed said port, the compression of saidcompression spring being determined to yield to the intake manifoldvacuum lowered to a predetermined level at which the vehicle isaccelerated or climbs up a hill, said solenoid valve device including asolenoid valve casing communicating spring mounted in said casing toforce said spool valve toward a position in which said land isolatessaid nozzle from said conduit, the compression of said compressionspring being determined to yield to the intake manifold vacuum loweredto said predetermined level, said solenoid valve device including asolenoid valve casing communicating with said casing of the spool valvedevice, said solenoid valve casing further communicating on one sidewith the intake manifold through a vacuum conduit and on the other withthe atmosphere, a moving core axially movably mounted in said solenoidvalve casing and acting at the same time as a valve member, said movingcore being normally forced into a position to isolate said vacuumconduit from said casing of said spool valve device by a spring action,and a solenoid coil associated with said moving core and connected witha power source through said control means, said moving core being movedto a position to permit said vacuum conduit to communicate with saidcasing of said spool valve device to cause said spool valve to be movedagainst the action of said spring in said spool valve device with saidcasing of the diaphragm valve device, said solenoid valve casing furthercommunicating on one side with the intake manifold through a vacuumconduit and on the other with the atmosphere, a moving core axiallymovably mounted in said solenoid valve casing and acting at the sametime as a valve member, said moving core being normally forced into aposition to isolate said vacuum conduit from said casing of saiddiaphragm valve device by a spring action, and a solenoid coilassociated with a said moving core and connected with a power sourcethrough said control means, said moving core being moved to a positionto permit said vacuum conduit to communicate with said casing of saidspool valve device to cause said diaphragm member to be moved againstthe action of said spring in said diaphragm valve device to a positionin which said valve element is moved to a position to open said portwhereby said exhaust recirculation nozzle is permitted to communicatewith said conduit when said solenoid coil of said solenoid valve deviceis excited by means of said control means.

5. A system according to claim 1, wherein said control means comprises avacuum switch connected with and controlled by a diaphragm device and avehicle speed switch connected with and controlled by a vehicle speeddetector which detects vehicle speeds selected by a transmission systemand delivers voltages proportional to the vehicle speeds detected, saidvacuum and engine speed switches being connected in series with a powersource and said solenoid coil, said diaphragm device comprising a vacuumchamber communicating with the intake manifold of the engine, adiaphragm member separating said vacuum chamber from the atmosphere, aconnecting rod rigidly connecting said diaphragm member and said vacuumswitch, and a compression spring mounted in said vacuum chamber to forcesaid diaphragm member to a position in which said connecting rod ismoved to close said vacuum switch, the compression of said spring beingdetermined to overpower the intake manifold vacuum lower than apredetermined level at which the vehicle is accelerated or climbs up ahill, and said vehicle speed detector being operative to cause saidvehicle speed switch to close when the detector detects a predeterminedrange of vehicle speed in which the vehicle is accelerated or climbs upa hill and delivers a voltage proportional to the vehicle speeddetected, whereby said solenoid coil of said control valve assembly isenergized and said valve element unseated when both of said vacuum andvehicle speed switches are closed concurrently.

References Cited UNITED STATES PATENTS 1,506,166 8/1924 Durrant l23-1l9A2,408,846 10/1946 Golden et a1. 123l 19A 2,722,927 11/1955 Corneliusl23l 19A WENDELL E. BURNS, Primary Examiner US. Cl. X.R.

